Motor vehicles are equipped with a wiper system having at least one wiper, wherein a wiper blade thereof wipes across glass surfaces in order to provide visibility for the occupants through the glass during periods of precipitation, or for cleaning of a glass surface. Wiper systems may employ one or more wipers (most commonly two) for the front windshield and, on some vehicles, one or more wipers for the rear window or windows. Indeed, some vehicles even have wipers for the headlights. What is typically common among wiper systems is an electronic control (manual switch or automatic) and one or more wipers interfaced with the electronic control, including an electric wiper motor, a wiper arm having a proximal end connected to the wiper motor, and a wiper blade assembly connected to a distal end of the wiper arm, wherein the wiper blade assembly carries an elastomeric wiper blade which wipes across the glass surface (typically in a reciprocating motion which pivots upon the wiper motor shaft) in squeegee fashion to wipingly remove debris and precipitation thereupon, and wherein the proximal end of the wiper arm includes an arm pivot which permits vertical movement of the wiper blade assembly toward and away from the glass surface, whereby a biasing spring associated with the wiper arm provides biasing of the wiper blade pressably onto the glass surface.
One annoying facet of the operation of wiper systems is when debris (which may be soluble, such as for example ice, or non-soluble, such as for example vegetation (in particular the stems of leaves), paper or dirt), gets trapped between the glass surface and the wiper blade. In such an instance, typically a streak (most often characterized as a water trail) appears on the glass surface after each wiping action due to the debris preventing wiping of the glass surface in the vicinity of its presence on the wiper blade. In order to rectify the situation, an occupant must exit the vehicle (when parked) and then manually shake the wiper arm by lifting and dropably releasing (i.e., letting the biasing spring to freely act on the wiper arm) the subject wiper arm (usually in a plurality of shake repetitions) in order to free the debris from the wiper blade. This manual procedure is unpleasant, especially when it must be performed during a time of heavy precipitation or at a location where standing beside the vehicle may present some hazard. Accordingly, it would be very advantageous if somehow a wiper blade could be freed of trapped debris without requiring manual removal.
In the prior art, U.S. Pat. No. 6,438,789B1, issued on Aug. 27, 2002 to Murawa et al., and assigned to the assignee hereof, describes an automatic wiper blade cleaning system which includes a nozzle body adapted to be disposed in the air intake plenum of a vehicle and connected to a source of fluid. The nozzle body has a nozzle that extends above a respective wiper blade in response to fluid pressure from the source of fluid to spray the fluid through the nozzle and onto the wiper blades to thereby clean the wiper blades. While this system works very well to remove ice and snow debris, which is dissolved by the fluid spray, it is less effective to remove non-soluble debris, such as the stem of a leaf trapped between the wiper blade and the glass surface.
Accordingly, what is needed in the art is a simple, effective and automatic debris removal apparatus for a wiper system that removes all kinds of debris, soluble and insoluble, which may be trapped between the wiper blade and the glass surface.